Prompting of Administrator Password When Installing New Software.

Question

I recently installed some software onto my Mac but I was not prompted to enter my administrator username and password as is usually the case (or so I thought).
Does anybody have any ideas as to why an administrator password is not always required when installing new software? The reason I ask is that I thought that this was one of the protections offered by the Mac to prevent unknown installations of Malware etc.
Thanks.

Answer 1

No password will ever be requested when you simply use drag and drop to install an application in the Applications folder. This is because you are a member of the admin group, and the admin group has authorized access to the Applications folder.
Nothing should install without your knowledge. If you are concerned about viruses and the like, then that's a different matter altogether from the question you asked. See this:
Do You Need Anti-Virus Protection for Your Mac?
According to Rich Mogull's article, Should Mac Users Run Antivirus Software?,
"The reality is that today the Mac platform is relatively safe. There are hundreds of thousands of viruses and other malicious software programs floating around for Windows, but less than 200 are known to target the Mac, and many of those are aimed at versions of the Mac OS prior to Mac OS X (and thus have no effect on a modern Mac).
It's not that Mac OS X is inherently more secure against viruses than current versions of Windows (although it was clearly more secure than Windows prior to XP SP2); the numerous vulnerabilities reported and patched in recent years are just as exploitable as their Windows equivalents. But most security experts agree that malicious software these days is driven by financial incentives, and it's far more profitable to target the most dominant platform."
Mr. Mogull is a computer security expert. I recommend reading the entire article as it is quite informative.
For additional information on viruses, trojans, and spyware visit The XLab FAQs and read the FAQs on viruses and spyware.